The present invention relates to methods for controlling certain insects and other pests by applying solutions of polyol esters, particularly sugar esters, directly to the pests.
A variety of pesticidal formulations are known for controlling insects, and other pests controlled by techniques similar to those used to control insects, in various environments. However, for most of these formulations the formulations contain one or more ingredients that have not previously been recognized as safe for use in connection with foods. Hence, the usage directions for such products, and/or the governmental approvals for using such products, often contain undesirable restrictions. Also the use of such pesticides is sometimes perceived by certain consumers as undesirable (e.g. the organic foods movement).
Some pesticides with improved toxicity and/or degradability characteristics, such as alkyl glycosides, have been developed. See e.g. U.S. Pat. No. 4,888,325. However, they are not optimal for certain uses.
As described in U.S. Pat. No. 6,419,941 (the disclosure of which is hereby incorporated by reference as if fully set forth herein), the art has also discovered a class of polyol esters. Some of these esters are sugar esters that naturally occur in certain plants. Others have been synthesized, such as by using an ester manufacturing process like those described in U.S. Pat. No. 5,756,716. These syntheses typically involved reacting an organic acid with a polyol (preferably a sugar type moiety in ring or linear form) in an esterification reaction, where the polyol contains five to twelve carbons. The polyol ester which results may be a monoester, or may be a mix of monoesters with multiple esterified variants. For purposes of the present invention polyols of sucrose, sorbitol, and xylitol are of greatest interest.
Certain sugar esters have previously been proposed to be used to spray plants/mushrooms so as to control certain soft body/sensitive pests such as psylla, sciarid flies, white flies, scales, hornworms, aphids and spider mites. For example, AVA Chemical Ventures (d/b/a/Avachem) commercially sells a 40% aqueous solution of sucrose octanoate for spray in diluted form on various plants/mushrooms. In this regard, they suggest diluting it and then spraying a 1.25% to 2.5% solution on mushrooms to control a sciarid fly infestation. Other Avachem literature suggests spraying plants with even lower concentrations of the formulation to control aphids and spider mites.
There have also been prior art suggestions to use such compounds (e.g. sucrose octanoate ester) to control Varroa mites infesting populations of adult honey bees. These compounds were perceived as being safe to the desirable commercial honey bee population, notwithstanding that it could be used to control such mites. Similarly, the USDA has published information on the use of sucrose octanoate which indicates that it is a desirable plant insecticide because it can control certain soft body/sensitive insects while not controlling certain hard body insects that are desirable (such as a lady beetle).
Hence, prior to the present invention, it was generally thought by the art that polyol esters like sucrose octanoate and sorbitol octanoate were not effective pesticides against more resilient types of pests. In fact, the art thought that this selectivity made these compounds particularly desirable for certain purposes.
Thus, a need still exists for pesticidal formulations that can control a variety of resilient insects/pests in an environmentally acceptable way, and improved techniques for using such formulations.